Biomedical subjects

Heinrich Göttlinger

Publications and source records attributed to Heinrich Göttlinger.

5 recordsLinked to original sources

PubMed2006

Release of autoinhibition converts ESCRT-III components into potent inhibitors of HIV-1 budding.

The endosomal sorting complex ESCRT-III, which is formed by the structurally related CHMP proteins, is engaged by HIV-1 to promote viral budding. Here we show that progressive truncations into the C-terminal acidic domains of CHMP proteins trigger an increasingly robust anti-HIV budding activity. Together with biochemical evidence for specific intramolecular interactions between the basic and acidic halves of CHMP3 and CHMP4B, these results suggest that the acidic domains are autoinhibitory. The acidic half of CHMP3 also interacts with the endosome-associated ubiquitin isopeptidase AMSH, and the coexpression of AMSH or its CHMP3-binding domain converts wild-type CHMP3 into a potent inhibitor of HIV-1 release. Point mutations in CHMP3 that prevent binding to AMSH abrogate this effect, suggesting that binding to AMSH relieves the autoinhibition of CHMP3. Collectively, our results indicate that CHMP proteins are regulated through an autoinhibitory switch mechanism that allows tight control of ESCRT-III assembly.

Acids↗

PubMed2006

Structural basis for budding by the ESCRT-III factor CHMP3.

The vacuolar protein sorting machinery regulates multivesicular body biogenesis and is selectively recruited by enveloped viruses to support budding. Here we report the crystal structure of the human ESCRT-III protein CHMP3 at 2.8 A resolution. The core structure of CHMP3 folds into a flat helical arrangement that assembles into a lattice, mainly via two different dimerization modes, and unilaterally exposes a highly basic surface. The C terminus, the target for Vps4-induced ESCRT disassembly, extends from the opposite side of the membrane targeting region. Mutations within the basic and dimerization regions hinder bilayer interaction in vivo and reverse the dominant-negative effect of a truncated CHMP3 fusion protein on HIV-1 budding. Thus, the final steps in the budding process may include CHMP protein polymerization and lattice formation on membranes by employing different bilayer-recognizing surfaces, a function shared by all CHMP family members.

Amino Acid Sequence↗

PubMed2005

Characterization of prototype foamy virus gag late assembly domain motifs and their role in particle egress and infectivity.

Foamy viruses (FV) are unusual among retroviruses since they require both Gag and Env structural proteins for particle egress. Recently significant progress has been made towards the mechanistic understanding of the viral release process, in particular that of retroviruses, and the viral domains and cellular pathways involved. However little is currently known about domains of FV structural proteins and cellular proteins engaged in this process. By mutational analysis of sequence motifs in prototype FV (PFV) Gag, bearing homology to known late assembly (L) domains, a PSAP motif with L domain function that was functionally interchangeable by heterologous L domains was identified. In contrast the inactivation of a PPPI motif had no significant influence on PFV particle release, although mutant viral particles displayed reduced infectivity. Similarly mutation of an evolutionary conserved YXXL motif revealed no classical L-domain function but resulted in release of noninfectious viruslike particles. Biochemical and electron microscopy analysis demonstrated that these mutant particles incorporated all viral structural proteins but contained aberrantly capsid structures, suggesting a role in capsid assembly for this PFV Gag sequence motif. In line with the mutational analysis, overexpression of dominant negative (DN) mutants and wild-type TSG101 but not the DN mutant of AIP-1/ALIX reduced PFV particle release and infectivity. Furthermore, DN mutants of Vps4A, Vps4B, and CHMP3 inhibited PFV egress and infectivity. Taken together these results demonstrate that PFV, like other viruses, requires components of the vacuolar protein sorting (VPS) machinery for egress and enters the VPS pathway through interaction with TSG101.

Amino Acid Motifs↗

PubMed2004

APOBEC3G incorporation into human immunodeficiency virus type 1 particles.

APOBEC3G is promiscuous with respect to its antiretroviral effect, requiring that it be packaged into diverse retrovirus particles. Here, we show that most virally encoded human immunodeficiency virus type 1 particle components are dispensable for APOPEC3G incorporation. However, replacement of the nucleocapsid (NC) Gag domain with a leucine zipper abolished APOBEC3G incorporation. Moreover, coprecipitation analysis showed that APOBEC3G-Gag interaction requires NC and nonspecific RNA. These observations suggest that APOBEC3G exploits an essential property of retroviruses, namely, RNA packaging, to infiltrate particles. Because it is, therefore, difficult to evolve specific sequences that confer escape from APOBEC3G, these findings may explain why lentiviruses evolved an activity that induces its destruction.

APOBEC-3G Deaminase↗

PubMed2003

Human and simian immunodeficiency virus capsid proteins are major viral determinants of early, postentry replication blocks in simian cells.

The cells of most Old World monkey species exhibit early, postentry restrictions on infection by human immunodeficiency virus type 1 (HIV-1) but not by simian immunodeficiency virus of macaques (SIV(mac)). Conversely, SIV(mac), but not HIV-1, infection is blocked in most New World monkey cells. By using chimeric HIV-1/SIV(mac) viruses capable of a single round of infection, we demonstrated that a major viral determinant of this restriction is the capsid (CA) protein. The efficiency of early events following HIV-1 and SIV(mac) entry is apparently determined by the interaction of the incoming viral CA and species-specific host factors.

Animals↗